Anglo-Australian Telescope

British astronomer Richard van der Riet Woolley pushed for a large optical telescope for the Southern Hemisphere in 1959. It took until September 1969 for plans to be finalised. The agreement initially committed the specification to a telescope design based on the American Kitt Peak telescope until its deficiencies were known. Both the horseshoe mount and the gearing system needed improvements. Although the revised gear system was considerably more expensive it was significantly more accurate, lending itself well to future applications. The mirror blank was made by Owens-Illinois in Toledo, Ohio. It was then transported to Newcastle, England, where Sir Howard Grubb, Parsons and Co took two years to grind and polish the mirror's surface. Mitsubishi Electric built the mount which was constructed by August 1973. First light occurred on 27 April 1974. The telescope was officially opened by Prince Charles on 16 October 1974. == Structure and telescope ==

The telescope is housed within a seven-story, circular, concrete building topped with a 36m diameter rotating steel dome. It was designed to withstand the high winds prevailing at that location. The slit is narrow. The dome is required to move with the telescope to avoid obstruction. The telescope has various foci for flexible instrumentation: originally there were three top-end rings which can be exchanged using the dome crane during the daytime. One was for f/3.3 prime-focus, with corrector lenses and a cage for a human observer taking photographs (rarely used after the 1980s); one has a large secondary mirror giving an f/8 Cassegrain focus; and a third top-end has smaller f/15 and f/36 secondary mirrors. A fourth top-end was built in the 1990s to give a 2-degree field of view at prime focus, with 400 optical fibres feeding the 2dF instrument and its later enhancements AAOmega and HERMES. == Instruments and Programs ==

The AAT is equipped with a number of instruments, including: • The Two Degree Field facility (2dF), a robotic optical fibre positioner for obtaining spectroscopy of up to 400 objects over a 2° field of view simultaneously. A 2dF and AAOmega program called OzDES ran for six years to obtain redshifts in the Dark Energy Survey (DES) observing fields for tens and thousands of galaxies, as well as obtain spectra of supernovae and other transients. • The University College London Échelle Spectrograph (UCLES), a high-resolution optical spectrograph which has been used to discover many extrasolar planets. • IRIS2, a wide-field infrared camera and spectrograph. • HERMES, a high resolution spectrograph to be used with the 2dF positioner, commissioned in 2015. HERMES is mainly being used for the 'Galactic Archaeology with Hermes' (GALAH) Survey, which aims to reconstruct the history of our galaxy's formation from precise multi-element (~25 elements) abundances of 1  million stars derived from HERMES spectra. • TAIPAN, a multispectral positioner and spectrograph (successor to HERMES and 2dF) which uses starbugs, small robots that move into position by vibrating, to position optical fibres. Comparisons == See also ==